1. Field of the Invention
The present invention relates to a fan casing with a noise-reducing structure. In particular, the present invention relates to a fan housing including an air inlet and an air outlet, with a supporting rib arranged in the air inlet extending along a longitudinal direction of the air outlet to reduce noise during operation.
2. Description of Related Art
A conventional fan, as illustrated in FIG. 1 of the drawings, includes a housing 10 in which an impeller 20 is rotatably received for creating an airflow when the impeller 20 is turned. The housing 10 includes an air inlet 11 and an air outlet 12. The airflow enters the housing 10 via the air inlet 11 and exits the housing 10 via the air outlet 12. The air inlet 11 is in a top side or bottom side of the housing 10 whereas the air outlet 12 is in a lateral side of the housing 10.
With reference to FIG. 1, a plurality of supporting ribs 111 are provided in the air inlet 11 and connected between an inner periphery of the air inlet 11 and an outer periphery of the air inlet 11 to support a motor base 112. To support the motor base 112 in a balanced manner, at least three supporting ribs 111 are provided. At lease one of the supporting ribs 111 is located in an area A (between two parallel, spaced lines in FIG. 1) adjacent to the air outlet 12 for balanced support of the motor base 112.
Although the supporting ribs 111 provide balanced support for the motor base 112, the supporting ribs 111 in the area “A” interfere with the airflow from the air inlet 11 to the air outlet 12. During operation of the motor, greater noise is generated at the supporting ribs 111 in the area A when the impeller 20 turns. Therefore, there is a need in improving disposition of the supporting ribs 111 to reduce the noise generated during operation.